This invention relates to the treatment and correction of venous insufficiency or varicose veins, and more particularly to a minimally invasive procedure using a catheter-based system to deploy an electrode for providing radio frequency (RF) energy, microwave energy, or thermal energy to shrink a vein intraluminally to change the fluid flow dynamics and to restore the competency of the venous valve and the proper function of the vein.
The human venous system of the lower limb consists essentially of the superficial venous system and the deep venous system with perforating veins connecting the two systems. The superficial system includes the long or great saphenous vein and the short saphenous vein. The deep venous system includes the anterior and posterior tibial veins which unite to form the popliteal vein, which in turn becomes the femoral vein when joined by the short saphenous vein.
The venous systems contain numerous one-way valves for directing blood flow back to the heart. Venous valves are usually bicuspid valves, with each cusp forming a sack or reservoir for blood which, under pressure, forces the free surfaces of the cusps together to prevent retrograde flow of the blood and allow antegrade flow to the heart. When an incompetent valve is in the flow path of retrograde flow toward the foot, the valve is unable to close because the cusps do not form a proper seal and retrograde flow of blood cannot be stopped.
Incompetence in the venous system can result from vein dilation, which causes the veins to swell with additional blood. Separation of the cusps of the venous valve at the commissure may occur as a result. The leaflets are stretched by the dilation of the vein and concomitant increase in the vein diameter which the leaflets traverse. Stretching of the leaflets of the venous valve results in redundancy which allows the leaflets to fold on themselves and leave the valve open. This is called prolapse, which can allow reflux of blood in the vein. Eventually the venous valve fails, thereby increasing the strain and pressure on the lower venous sections and overlying tissues. Two venous diseases which often involve vein dilation are varicose veins and chronic venous insufficiency.
The varicose vein condition includes dilatation and tortuosity of the superficial veins of the lower limb, resulting in unsightly discoloration, pain and ulceration. Varicose veins often involve incompetence of one or more venous valves, which allow reflux of blood from the deep venous system to the superficial venous system or reflux within the superficial system. Current treatments include such invasive open surgical procedures as vein stripping, sclerotherapy, and occasionally, vein grafting, venous valvuloplasty, and the implantation of various prosthetic devices. The removal of varicose veins from the body can be a tedious, time-consuming procedure having a painful and slow healing process. Complications, scarring, and the loss of the vein for future cardiac and other by-pass procedures may also result. Along with the complications and risks of invasive open surgery, varicose veins may persist or reoccur, particularly when the valvular problem is not corrected. Due to the long, arduous, and tedious nature of the surgical procedure, treating multiple venous sections can exceed the physical stamina of the physician, and thus render complete treatment of the varicose vein conditions impractical.
Chronic venous insufficiency (CVI) is a problem caused by hydrodynamic forces acting on the tissues of the body, especially the legs, ankles and feet. As the veins dilate due to increased pressure, the valves in the veins fail. This causes the pressure to increase on the next valve and vein segment down, causing those veins to dilate, and as this continues, the valves in the veins eventually all fail. As they fail, the effective height of the column of blood above the feet and ankles grows, and the weight and hydrostatic pressure exerted on the tissues of the ankle and foot increases. When the weight of that column reaches a critical point from the valve failures, ulcerations of the ankle begin to form, which start deep and eventually come to the surface. These ulcerations do not heal easily because the weight of blood which caused them continues to persist, and have the tendency to enlarge the ulcer.
Chronic venous insufficiency often consists of hypertension of the lower limb in the deep, perforating and often superficial veins, and may result in discoloration, pain, swelling and ulceration. Existing treatments for chronic venous insufficiency are often less than ideal. These treatments include the elevation of the legs, compressing the veins externally with elastic support hose, and surgical repair by grafting vein sections with healthy valves from the arm into the leg. These methods have variable effectiveness. Moreover, invasive surgery has its associated complications with risk to life and expense. Similarly, the palliative therapies require major lifestyle changes for the patient. For example, the ulcers will reoccur unless the patient continues to elevate the legs and use support hose continuously throughout the life of the patient.
Due to the time-consuming and invasive nature of the current surgical treatments, such as vein grafting, typically only one valve is treated during any single procedure. This greatly limits the ability of the physician to fully treat patients suffering from chronic venous insufficiency. Every instance of invasive surgery, however, has its associated complications with risk to life and expense.
The ligation of vascular lumen by tying a suture around them, cauterization or coagulation using electrical energy from an electrode has been employed as an alternative to stripping, or the surgical removal of such veins. However, ligation procedures close off the lumen, essentially destroying their functional capability. For example, it is known to introduce an electrode into the leg of a patient, and position the electrode adjacent to the exterior of the varicose veins to be treated. Through a small stab incision, a probe is forced through the subcutaneous layer between the fascia and the skin, and then to the various veins to be destroyed. Electrodes at the outer end of the probe are placed adjacent to the varicose veins. Once properly positioned, an alternating current of 500 kilohertz is applied to destroy the adjacent varicose veins by fulguration. The fulgurated veins lose the function of allowing blood to flow through, and are no longer of use. For example, ligating the saphenous vein would render that vein unavailable for harvesting in other surgical procedures such as coronary by-pass operations. Ligation techniques which functionally destroy the vein lumen would appear to be inappropriate to a corrective procedure for restoring and maintaining the function of the vein.
A need exists in the art to treat dilated veins, such as those resulting in varicose veins or from venous insufficiency, which maintains the patency of the veins for venous function and yet restores valvular competency.
Briefly, and in general terms, the present invention provides a less invasive and faster method for solving the underlying problems of varicose veins and venous insufficiency, and uses a novel repair system, including a catheter for placement of an electrode for delivering radio frequency energy. The present invention includes a method of applying energy to cause shrinkage of a vein, the method comprising the steps of introducing a catheter having a working end and means for heating located at the working end, to a treatment site in a vein; positioning the means for heating at the treatment site in the vein; applying energy from the means for heating to controllably heat the treatment site and cause shrinkage of the vein; and terminating the emission of energy from the means for heating after sufficient shrinkage of the vein has occurred so as to restore valvular competency or so that the vein remains patent so as to continue to function as a blood conduit.
The method of the present invention is a minimally invasive procedure which eliminates the need for open surgical procedures for venous repair, including venous valvuloplasty, and the transplantation of an arm vein into the leg.
An apparatus for performing the method of applying radiant energy to cause shrinkage of a vein, comprises a catheter having a working end, means for heating a venous treatment area to cause shrinkage of the vein, wherein the means for heating is located at the working end of the catheter, and means for preventing further shrinkage after sufficient shrinkage of the vein, so that the vein continues to function. The heating means may include RF electrodes to heat and shrink the vein. Balloons, or other mechanisms for controlling the outer diameter of the heating means, may be used to limit the amount of shrinkage. Feedback control systems may be applied to these mechanisms, or may be used to control the application of energy to heat the venous tissue, in order to control the amount of shrinkage.
Features of the present invention include restoring the competence of venous valves, normalizing flow patterns, dynamics, and pressure, and reducing sections of dilated varicose veins to a normal diameter for cosmetic purposes. The treated veins remain patent and can continue to function and return blood to the heart.
One feature of the present invention is to provide a procedure for restoring venous valvular competency by controllably shrinking the otherwise dilated lumen of the vein to a desired diameter.
Another feature of the present invention is to control or adjust the effective diameter of the catheter or electrode configuration in order to control the amount of circumferential shrinking experienced by the vein wall. An extendable member located adjacent to the working end of the catheter can increase the effective diameter of the catheter and limit the shrinkage of the vein.
Another feature of the present invention is to provide a catheter electrode which generates a radio frequency field around the circumference of the catheter in order to shrink the vein wall circumferentially and omnidirectionally while minimizing lengthwise contraction when the catheter electrode is positioned intraluminally within the vein.
Yet another feature of the present invention is to generate a field at a specific frequency around the catheter in order to minimize coagulation within the vein, and to control the spread of heating within the venous tissue.
An additional feature of the present invention is to protect the venous valve leaflets by minimizing the heating effect on the venous valves by the selective positioning of the electrodes within the vein.
Another feature of the present invention is to deliver cooling fluid to the bloodstream in order reduce the likelihood of heating the blood to a point of coagulation.
An additional feature of the present invention is to prevent shrinkage of the vein past the end of the catheter.
Another feature of the present invention is to maintain the electrodes in apposition to the venous tissue to ensure that the heat is delivered towards the venous tissue, and not the blood moving through the vein.
Another feature of the present invention is to use electrodes which are bowable members that can be deflected radially outward for maintaining contact with the venous tissue. The bowable members are conductive longitudinal electrodes substantially covered by an insulating film, except for the portion which is to come into apposition with the venous tissue.
Another feature of the present invention is a balloon located on one side of the catheter having electrodes on the opposite side. Inflation of the balloon will move the electrodes into apposition with the vein wall on the opposite side.
Yet another feature of the present invention is to provide a procedure which can treat multiple venous sites quickly and easily.
An additional feature of the present invention is that no foreign object or prothesis remain in the vasculature after treatment.